Factual error: During the performance by Sweden there are 7 people on stage, meaning this entry would be disqualified due to the rules of the contest which state no more than 6 people are allowed on stage.
Character mistake: The Rufus hologram states that he first brought the phone booth to the Chosen Ones (Bill and Ted) in 1989, referencing events of the original film. While that was the year the first movie came out, it took place in 1988 (indicated by the opening title card and dialogue throughout the movie).
Continuity mistake: The protagonist just arrived to his college. Long shot as he gets off the taxi, and to the right of the frame you see a group of 3 girls crossing the street and walking on the lawn. Cut, and the 3 girls have yet to cross. (00:07:00)
Deliberate mistake: In the Spanish release, the name of the family store is written in Spanish, but inside the place it's in English everywhere. This is a very common mistake in foreign kids' films released in Spain.
Continuity mistake: Maggie was holding two bottles (clear containing a green liquid) in her right hand and set them on the table together with one at an angle behind the other. She moved her hand away and when the camera shifted to a wide view, the bottles were side-by-side (horizontal to the screen) with more space between them. Also, both bottles were almost full, but had less in them when Maggie handed one to Grace at the airport. (Maggie may have had a sip out of hers, but not Grace's; both looked unopened). (00:03:33 - 00:04:25)